hi guys
I have got a problem with the cutoff distance.
I want to solve a 3D poiseuille flow using lammps.
it works and goes correct when I use 1.2 or lower for the cutoff
distance value, but as soon as I put more than that, the system
collapses! really it does
cuz when i visual the trajectory file using vmd, I can see that.
should I change another parameter with changing cutoff distance?
if anyone can help me
this is my input file.
If anyone can help me , I'd greatly appreciate it.
thanks
M.rezaee
# 3D Poiseuille Flow
dimension 3
boundary p p p
atom_style atomic
neighbor 0.3 bin
neigh_modify delay 5
# geometry
lattice fcc 0.6
region box block 0 10.6 0 10.44 0 10.6 units box
create_box 2 box
# create atomic lattices
mass 1 1.0
mass 2 1.0
region 1 block INF INF 0.0 1.66666 INF INF units box
region 20 block INF INF 0.0 0.83333 INF INF units box
region 21 block INF INF 0.83333 1.66666 INF INF units box
#region 22 block INF INF 1.66666 2.5 INF INF units box
region 2 intersect 2 1 box side out units box
create_atoms 1 region 2
lattice none
lattice fcc 0.85
create_atoms 2 region 1
group wall region 1
group first region 20
group second region 21
#group third region 22
group flow subtract all wall
# potential calculation
pair_style lj/cut 1.22
pair_coeff * * 1.0 1.0
#pair_coeff 2 2 1.0 1.0
#pair_coeff 1 2 1.0 1.18
# initial velocities
compute mobile flow temp
compute stationary wall temp
fix 1 all nve
# Poiseuille flow
minimize 1.0e-3 1.0e-5 100 1000
fix 2 flow addforce 0.037 0.0 0.0
# wall
fix 7 wall temp/rescale 1 1.0 1.0 0.0001 1.0
fix 5 wall spring/self 57.1
fix 20 first recenter NULL INIT NULL
fix 21 second recenter NULL INIT NULL
#fix 22 third recenter NULL INIT NULL
# run
timestep 0.00467
thermo 1000
thermo_modify temp mobile
dump 1 flow custom 500000 dump2.flow y vx
dump 2 all atom 50000 flow2.lammpstrj
#dump 3 all atom 100 *.xyz
#dump_modify 3 header xyz
fix ans flow ave/spatial 2 5000 500000 y center 0.2 vx
file fix2.dat
run 500000